U.S. President Barack Obama on Thursday urged all Americans to unite behind President-elect Donald Trump.

"We're Americans first," Obama said in a speech at the White House.

“Yesterday, before votes were tallied, I shot a video in which I said to the American people, the sun would come up in the morning and that is one bit of prognosticating that actually came true," he said. “I know everybody had a long night. I did as well.”

Obama said he spoke directly to Trump after the election results came out.

“It is no secret that the president-elect and I have some pretty significant differences. But remember that eight years ago, President Bush and I had some pretty significant differences," he added. "The presidency and vice presidency is bigger than any of us."

"We are now all rooting for his success in uniting and leading this country. The peaceful transfer of power is one of the hallmarks of our democracy," he said.

Obama said he is proud of his former secretary of state Hillary Clinton, who lost the presidential race to Trump.

“I could not be prouder of her. I am proud of her. A lot of Americans look up to her. Her candidacy and nomination was historic," he said.

He urged Democratic Party supporters to support the incoming president.

“Everybody is sad when their side loses their election. But the day after, we have to remember that we’re actually all on the same team. We're patriots first," he said.

“That’s what I heard when I spoke to (Donald Trump) directly, and I was heartened by that. That’s what our country needs," Obama said.

He added that Clinton's supporters should not lose hope.

"But that’s the nature of campaigns, that’s the nature of democracy," he said. "To the young people who got into politics for the first time and may be discouraged by the results, I want you to know, you have to stay encouraged. Don’t get cynical, fighting for what is right is important."

"We lick our wounds, we brush ourselves off, we get back in the arena. We move forward. That presumption of good faith is essential to a vibrant democracy," he added.

"Ultimately, we’re all on the same team," Obama said.

Clinton early Thursday morning also conceded the U.S. presidential race to Trump, in a speech at a hotel in Manhattan, New York.

She said Americans should accept the results of the election.

"Donald Trump is going to be our president. We owe him an open mind and a chance to lead," she said in a speech applauded several times by her staff and supporters.

Clinton said she has congratulated Trump and offered to work with him. "I hope that he will be a president for all of our country."

“I'm sorry that we did not win this election for the values we all share," she said. "This is painful, and it will be for a long time. But I want you to remember this. Our campaign was never about one person. It was about building a country that we love. We have seen that our country was more deeply divided than we ever thought."

Clinton entered election day leading in national polls, with what political pundits said was a clearer path to the 270 electoral votes needed to win the race.

However, her path narrowed until it closed completely.

Trump won after capturing Wisconsin's 10 electoral votes, putting him over the 270 threshold.

The outspoken billionaire scored key wins in three major swing states - Ohio, Florida, and North Carolina.

Trump praised Clinton in his victory speech and called on Americans to unite following one of the closest presidential elections in U.S. history.

"She congratulated us. It’s about us. On our victory, and I congratulated her and her family on a very, very hard-fought campaign," he said. "I mean, she fought very hard. Hillary has worked very long and very hard over a long period of time, and we owe her a major debt of gratitude for her service to our country." - with reports from Reuters, ANC